Vehicles, in particular aircraft and marine vehicles, suffer the risk of collision with other vehicles, aircraft, trains, terminal structures, construction equipment and other obstacles on the ground and especially on runways where aircraft are concerned. Weather radar is often turned off on the ground because of the relative high power of the transmitter operating in the X-band or higher and because of the ground clutter return.
FIG. 1 is a plan view of a hypothetical airport 102. The hypothetical airport 102 includes a runway 104, several taxiways 106, a plurality of tarmac areas 108, and a plurality of terminal buildings 110. A plurality of parked aircraft 112 are illustrated in various locations about the airport 102. A plurality of service vehicles 114, such as fuel trucks, luggage carts, construction equipment, and emergency vehicles, are located on the taxiways 106 and the tarmac 108. A plurality of parked automobiles 116 are parked in parking areas about the various buildings 110. Around the airport 102 are a plurality of forested areas 118, with relatively tall trees, and a brush area 120, with moderately high brush that is less than the height of the trees of the forested areas 118.
Further, an aircraft 122 is on the runway 104. The aircraft 122 may be stationary or moving, depending upon the situation. An aircraft 124 is at the end of the runway 104. The aircraft 122 will be causing a radar return that is received by the radar system of the aircraft 124.
Also, various sizes and types of signs 126 are positioned along the edges of the runway 104 and/or the taxiways 106 to provide guidance to the aircraft 122, 124. These signs 126 cause radar returns which further clutter the display of the radar information. Often, many signs 126 are on the runway 104 and/or the taxiways 106, of which only a few are conceptually illustrated. Further, there may be other structures, such as lights or the like (not shown) which also cause radar returns that also clutter the display.
FIG. 2 is a prior art conceptual diagram of a mapping 202 of the hypothetical airport 102 of FIG. 1. The map of the airport 102 is derived from information residing in a map database. The mapping information includes information identifying geographic location of the various features of the airport 102, such as the boundaries of the runway 104, the taxiways 106, the tarmac areas 108 and the buildings 110. For example, the boundaries of the runway 104 may be defined as a polygon or the like where the corner locations are identified by geographic coordinates. Other objects, such as the signs 126, may also be identified by location in the mapping information.
FIG. 3 is a hypothetical plan view of radar returns 302 generated by the radar system of the aircraft 124. The radar returns 302 are superimposed over the hypothetical airport 102 of FIG. 1 to illustrate the relative location of the airport 102 when the aircraft 124 is at the end of the runway 104. The radar sweep range of ninety degrees (90°), conceptually illustrated by the lines 304, shows large areas of radar returns 302 from the buildings 110, the parked aircraft 112, and the service vehicles 114. Further, large areas of radar returns 302 are illustrated for the forested areas 118, with relatively tall trees, and the brush area 120, with moderately high brush. A plurality of radar returns 306 are illustrated from the signs 126 along the runway 104. A radar return 308 is illustrated from the aircraft 122. Smaller radar returns 310 are illustrated, and may likely be reflections from very small objects such as lights or even debris.
It is appreciated that the illustrated radar return information, typically presented as radar returns only (without being superimposed on a map of the airport 102) does not present much useful information to the crew of the aircraft 124. In reality, the most relevant piece of information to the crew of the aircraft 124 is the presence of the aircraft 122 on the runway 104 (which may constitute a potential hazard to the aircraft 124). In such situations, the radar returns 302 displayed on a radar display include so much information, most of which is not relevant to the crew of the aircraft 124, that the crew is not likely to use the presented radar information while on the ground. Often, the radar system of the aircraft 124 is turned off.
Accordingly, a radar system is needed that can be taken anywhere in the world with vehicles, such as an aircraft or a marine vessel, which provides radar return information that does not display non-relevant radar information of the airport or other environment infrastructures.